One conventional technique for processing of cracked naphthas involves performing a selective hydrodesulfurization of the cracked naphtha. A selective hydrodesulfurization refers to a process where sulfur is removed from the naphtha while minimizing the amount of olefin saturation that occurs in the reaction. Avoiding olefin saturation is valuable, as it leads to a higher octane naphtha product. Retaining a higher octane value allows a selectively hydrodesulfurized feed to be used as a naphtha fuel stock without having to use a reforming step.
The catalysts used for a selective hydrodesulfurization process typically include a combination of a Group VI metal and a Group VIII metal on a suitable support, such as a catalyst including cobalt and molybdenum on an alumina support. A number of compounds have previously been identified as reaction inhibitors for selective hydrodesulfurization catalysts. These reaction inhibitors reduce the activity of the catalyst for performing hydrodesulfurization.
U.S. Pat. No. 7,507,328 describes a method for selective naphtha hydrodesulfurization and mercaptan decomposition. An olefinic naphtha stream is selectively desulfurized in a hydrodesulfurization reaction stage. The hydrodesulfurized effluent stream is separated into a light and heavy liquid fraction, and the heavier fraction is further processed in a mercaptan destruction stage to reduce the content of mercaptan sulfur in the final product.